Characterization of the MitoPark mouse model of Parkinson’s disease for neurotoxicity and neuroprotection studies

Parkinson’s disease (PD) is a chronic, progressive neurodegenerative disorder affecting about one million people in the United States and an estimated 10 million people worldwide. Although the pathological features of the disease, including dopaminergic neuronal loss and protein aggregation in the nigrostriatal tract are well understood, no cure or therapy exists that can decelerate or halt the neurodegenerative process. The exact mechanisms leading to cell death are still unresolved and advances in drug discovery for PD have been hampered by the lack of animal models that faithfully recapitulate the chronic, progressive nature of the disease, the full range of symptomology, and the underlying pathophysiological pathways. A recent transgenic mouse model, referred to as “MitoPark”, was created by selective inactivation of mitochondrial transcription factor A (TFAM) in the nigrostriatal pathway through control of the dopamine transporter (DAT) promotor by utilizing Cre/LoxP recombination. MitoPark mice model human PD by exhibiting a progressive course of the phenotypic manifestations and neurodegeneration, protein inclusions in nigral tissues, L-DOPA responsiveness, and adult-onset of disease. Considering that nonmotor symptoms reduce the quality of life and increase the cost of healthcare for PD patients, we characterized the full range of symptomatology in the MitoPark model. Similar to human PD, our MitoPark data suggest that many nonmotor symptoms, including cognitive deficits in learning and memory, olfactory discrimination, and neuropsychiatric deficits, are present in the model prior to severe motor dysfunction. Moreover, we have identified changes in neurogenesis, oxidative stress markers, and neurochemistry in the brain that correlate with the nonmotor symptoms observed. Furthermore, we have established that neuroinflammation (as a result of reactive microgliosis) and altered neurogenesis (subsequent to dopamine depletion) are present in later stages of the disease in this mouse model, making it particularly valuable for translational neurotoxicity and drug discovery studies. We also demonstrate that manganese, an environmentally relevant toxin linked to increased PD risk, can exacerbate some of these effects and accelerate disease onset in MitoPark mice. Finally, we explore two promising therapeutic options for PD: a mitochondrially targeted antioxidant and a neuroprotective protein. Our data demonstrate that Mito-apocynin treatment effectively attenuates progressive motor deficits, neuroinflammation, oxidative stress, and neurodegeneration in a comprehensive PD model via NOX2 inhibition in microglia and antioxidant effects in neurons. By expanding on recent work in our laboratory showing that Prokineticin-2 (PK2) serves a compensatory neuroprotective role in PD models, we identified a new mechanism by which PK2 may exert its effect: promoting neural stem cell proliferation and differentiation. Taken together, we have identified salient features of PD disease progression in a mouse model and applied the model to elucidate gene-environment interactions and to evaluate novel therapeutic strategies

Allo-suckling occurrence and its effect on lactation and nursing duration in harbour seals (Phoca vitulina) in Orkney, Scotland

This study was funded by Scottish Government (grant number MMSS/002/15).Fostering and allo-suckling are widespread among pinnipeds, and several hypotheses have been formulated to explain their occurrence. Here, we describe the occurrence of allo-suckling in harbour seals from photo-identification data of females and pups in Orkney (Scotland) during the pupping seasons between 2016 and 2019. We used a generalised linear model framework to investigate the effect of allo-suckling on the duration of lactation (females) and of nursing period (pups). A generalised additive model framework was used to explore how the probability of allo-suckling varied throughout the pupping season, and with changes in mother-pup separation time. Allo-suckling was observed in 31 females, at higher rates (18–37% of lactating females and 18–47% of the pups every year) than those observed in other phocid populations, with 13 females allo-suckling in multiple years. The duration of the pups’ nursing period was not affected by allo-suckling occurrence. However, females in mother-pup pairs where both mother and pup allo-suckled had longer lactation duration than when only the pup allo-suckled, or than in pairs where no allo-suckling was observed. The probability of allo-suckling increased during the pupping season and with increased mother-pup separation time. However, the proximate causes and the consequences on future reproductive output and pup survival remain unknown.Publisher PDFPeer reviewe

Mito-metformin protects against mitochondrial dysfunction and dopaminergic neuronal degeneration by activating upstream PKD1 signaling in cell culture and MitoPark animal models of Parkinson’s disease

Impaired mitochondrial function and biogenesis have strongly been implicated in the pathogenesis of Parkinson’s disease (PD). Thus, identifying the key signaling mechanisms regulating mitochondrial biogenesis is crucial to developing new treatment strategies for PD. We previously reported that protein kinase D1 (PKD1) activation protects against neuronal cell death in PD models by regulating mitochondrial biogenesis. To further harness the translational drug discovery potential of targeting PKD1-mediated neuroprotective signaling, we synthesized mito-metformin (Mito-Met), a mitochondria-targeted analog derived from conjugating the anti-diabetic drug metformin with a triphenylphosphonium functional group, and then evaluated the preclinical efficacy of Mito-Met in cell culture and MitoPark animal models of PD. Mito-Met (100–300 nM) significantly activated PKD1 phosphorylation, as well as downstream Akt and AMPKα phosphorylation, more potently than metformin, in N27 dopaminergic neuronal cells. Furthermore, treatment with Mito-Met upregulated the mRNA and protein expression of mitochondrial transcription factor A (TFAM) implying that Mito-Met can promote mitochondrial biogenesis. Interestingly, Mito-Met significantly increased mitochondrial bioenergetics capacity in N27 dopaminergic cells. Mito-Met also reduced mitochondrial fragmentation induced by the Parkinsonian neurotoxicant MPP+ in N27 cells and protected against MPP+-induced TH-positive neurite loss in primary neurons. More importantly, Mito-Met treatment (10 mg/kg, oral gavage for 8 week) significantly improved motor deficits and reduced striatal dopamine depletion in MitoPark mice. Taken together, our results demonstrate that Mito-Met possesses profound neuroprotective effects in both in vitro and in vivo models of PD, suggesting that pharmacological activation of PKD1 signaling could be a novel neuroprotective translational strategy in PD and other related neurocognitive diseases

Clinical Impact of the Line Probe Assay and Xpert® MTB/RIF Assay in the Presumptive Diagnosis of Drug-Resistant Tuberculosis in Brazil: A Pragmatic Clinical Trial

Background: Rapid molecular methods such as the line probe assay (LPA) and Xpert® MTB/RIF assay (Xpert) have been recommended by the World Health Organization for drug-resistant tuberculosis (DR-TB) diagnosis. We conducted an interventional trial in DR-TB reference centers in Brazil to evaluate the impact of the use of LPA and Xpert. Methods: Patients with DR-TB were eligible if their drug susceptibility testing results were available to the treating physician at the time of consultation. The standard reference MGITTM 960 was compared with Xpert (arm 1) and LPA (arm 2). Effectiveness was considered as the start of the appropriate TB regimen that matched drug susceptibility testing (DST) and the proportions of culture conversion and favorable treatment outcomes after 6 months. Results: A higher rate of empirical treatment was observed with MGIT alone than with the Xpert assay (97.0% vs. 45.0%) and LPA (98.2% vs. 67.5%). Patients started appropriate TB treatment more quickly than those in the MGIT group (median 15.0 vs. 40.5 days; p<0.01) in arm 1. Compared to the MGIT group, culture conversion after 6 months was higher for Xpert in arm 1 (90.9% vs. 79.3%, p=0.39) and LPA in arm 2 (80.0% vs. 83.0%, p=0.81). Conclusions: In the Xpert arm, there was a significant reduction in days to the start of appropriate anti-TB treatment and a trend towards greater culture conversion in the sixth month

Mito-Apocynin Prevents Mitochondrial Dysfunction, Microglial Activation, Oxidative Damage, and Progressive Neurodegeneration in MitoPark Transgenic Mice

Aims: Parkinson\u27s disease (PD) is a neurodegenerative disorder characterized by progressive motor deficits and degeneration of dopaminergic neurons. Caused by a number of genetic and environmental factors, mitochondrial dysfunction and oxidative stress play a role in neurodegeneration in PD. By selectively knocking out mitochondrial transcription factor A (TFAM) in dopaminergic neurons, the transgenic MitoPark mice recapitulate many signature features of the disease, including progressive motor deficits, neuronal loss, and protein inclusions. In the present study, we evaluated the neuroprotective efficacy of a novel mitochondrially targeted antioxidant, Mito-apocynin, in MitoPark mice and cell culture models of neuroinflammation and mitochondrial dysfunction. Results: Oral administration of Mito-apocynin (10 mg/kg, thrice a week) showed excellent central nervous system bioavailability and significantly improved locomotor activity and coordination in MitoPark mice. Importantly, Mito-apocynin also partially attenuated severe nigrostriatal degeneration in MitoPark mice. Mechanistic studies revealed that Mito-apo improves mitochondrial function and inhibits NOX2 activation, oxidative damage, and neuroinflammation. Innovation: The properties of Mito-apocynin identified in the MitoPark transgenic mouse model strongly support potential clinical applications for Mito-apocynin as a viable neuroprotective and anti-neuroinflammatory drug for treating PD when compared to conventional therapeutic approaches. Conclusion: Collectively, our data demonstrate, for the first time, that a novel orally active apocynin derivative improves behavioral, inflammatory, and neurodegenerative processes in a severe progressive dopaminergic neurodegenerative model of PD. Antioxid. Redox Signal. 27, 1048–1066

Analysis of shared heritability in common disorders of the brain

ience, this issue p. eaap8757 Structured Abstract INTRODUCTION Brain disorders may exhibit shared symptoms and substantial epidemiological comorbidity, inciting debate about their etiologic overlap. However, detailed study of phenotypes with different ages of onset, severity, and presentation poses a considerable challenge. Recently developed heritability methods allow us to accurately measure correlation of genome-wide common variant risk between two phenotypes from pools of different individuals and assess how connected they, or at least their genetic risks, are on the genomic level. We used genome-wide association data for 265,218 patients and 784,643 control participants, as well as 17 phenotypes from a total of 1,191,588 individuals, to quantify the degree of overlap for genetic risk factors of 25 common brain disorders. RATIONALE Over the past century, the classification of brain disorders has evolved to reflect the medical and scientific communities' assessments of the presumed root causes of clinical phenomena such as behavioral change, loss of motor function, or alterations of consciousness. Directly observable phenomena (such as the presence of emboli, protein tangles, or unusual electrical activity patterns) generally define and separate neurological disorders from psychiatric disorders. Understanding the genetic underpinnings and categorical distinctions for brain disorders and related phenotypes may inform the search for their biological mechanisms. RESULTS Common variant risk for psychiatric disorders was shown to correlate significantly, especially among attention deficit hyperactivity disorder (ADHD), bipolar disorder, major depressive disorder (MDD), and schizophrenia. By contrast, neurological disorders appear more distinct from one another and from the psychiatric disorders, except for migraine, which was significantly correlated to ADHD, MDD, and Tourette syndrome. We demonstrate that, in the general population, the personality trait neuroticism is significantly correlated with almost every psychiatric disorder and migraine. We also identify significant genetic sharing between disorders and early life cognitive measures (e.g., years of education and college attainment) in the general population, demonstrating positive correlation with several psychiatric disorders (e.g., anorexia nervosa and bipolar disorder) and negative correlation with several neurological phenotypes (e.g., Alzheimer's disease and ischemic stroke), even though the latter are considered to result from specific processes that occur later in life. Extensive simulations were also performed to inform how statistical power, diagnostic misclassification, and phenotypic heterogeneity influence genetic correlations. CONCLUSION The high degree of genetic correlation among many of the psychiatric disorders adds further evidence that their current clinical boundaries do not reflect distinct underlying pathogenic processes, at least on the genetic level. This suggests a deeply interconnected nature for psychiatric disorders, in contrast to neurological disorders, and underscores the need to refine psychiatric diagnostics. Genetically informed analyses may provide important "scaffolding" to support such restructuring of psychiatric nosology, which likely requires incorporating many levels of information. By contrast, we find limited evidence for widespread common genetic risk sharing among neurological disorders or across neurological and psychiatric disorders. We show that both psychiatric and neurological disorders have robust correlations with cognitive and personality measures. Further study is needed to evaluate whether overlapping genetic contributions to psychiatric pathology may influence treatment choices. Ultimately, such developments may pave the way toward reduced heterogeneity and improved diagnosis and treatment of psychiatric disorders

Genomic Relationships, Novel Loci, and Pleiotropic Mechanisms across Eight Psychiatric Disorders

Genetic influences on psychiatric disorders transcend diagnostic boundaries, suggesting substantial pleiotropy of contributing loci. However, the nature and mechanisms of these pleiotropic effects remain unclear. We performed analyses of 232,964 cases and 494,162 controls from genome-wide studies of anorexia nervosa, attention-deficit/hyper-activity disorder, autism spectrum disorder, bipolar disorder, major depression, obsessive-compulsive disorder, schizophrenia, and Tourette syndrome. Genetic correlation analyses revealed a meaningful structure within the eight disorders, identifying three groups of inter-related disorders. Meta-analysis across these eight disorders detected 109 loci associated with at least two psychiatric disorders, including 23 loci with pleiotropic effects on four or more disorders and 11 loci with antagonistic effects on multiple disorders. The pleiotropic loci are located within genes that show heightened expression in the brain throughout the lifespan, beginning prenatally in the second trimester, and play prominent roles in neurodevelopmental processes. These findings have important implications for psychiatric nosology, drug development, and risk prediction.Peer reviewe